

By JAMES R. CAMERON 

19 2 2 

Price 5 0 cents 


Published by 

THE TECHNICAL BOOK CO. 

130-132 W. 42nd ST., NEW YORK CITY 











RADIO 

DICTIONARY 


WITH USEFUL TABLES 
AND INFORMATION 
FOR THE AMATEUR 


By 

AMES R. (^AMERON 

Author of 

u Motion Picture ‘Projection" 

“ Radio for Ti-ginners" 

“ Elementary Elects tcity" 

“Text Book on Wireless" 
Etc., etc. 


) , ' 

1922 


PUBLISHED BY 

THE TECHNICAL BOOK COMPANY 

1 30 West 42ND St., New York City 







Copyright in the United States, 1922 
Copyright in Great Britain, 1922 
Copyright in Canada, 1922 

By James R. Cameron 


Entered, at Stationers Hall , London , 
England 


'fRIGHT OFFICF 
3GT 12 fMS 


Commanday-Roth Co., Inc., Printers, N 





DICTIONARY 
OF RADIO TERMS 

A Glossary of Radio Words 
and Their Definitions 

Compiled by JAMES R. CAMERON 

A. C. ALTERNATING CURRENT—A current that 
changes its flow of direction a given number of 
times a second, according to the construction of the 
alternator. 

ACCELERATION—Rate of change of velocity. 

V ACCUMULATOR—A storage battery. A 

ACLINIC LINE—The line that represents the mag¬ 
netic equator. 

ACOUSTICS—The science of sound. 

ACTINIC RAYS—The rays at the violet end of the 
spectrum. 

ACTINOMETER—A photometer; a meter for meas¬ 
uring the sun’s rays. 

ACTUAL HORSE POWER—The exact useful power 
given out by a machine; found by subtracting the 
power used by the machine itself from the indicated 
horsepower. 

ADAMANT—A substance of extreme hardness such 
as the diamond.*! ' 

ADJUSTABLE CONDENSER—A condenser, any 
part of which may be cut in or out of the circuit; 
thus varying its capacity. 

v ADMITTANCE—One ohm has an admittance of one 
mho: the reciprocal of impedence. 
v AERIAL—A system of wires used to radiate or re¬ 

ceive energy in the form of electro-magnetic waves. 
The wires should be strung clear of, and insulated 
from all surrounding objects. 

AEROMETER—A meter for measuring the tension 
of the air. 

ALIGN—To place or form in line. 

ALLOY—A mixture of two or more metals. 

ALTERNATOR—An alternating current dynamo. 

ALTERNATING CURRENT—See A. C. 


5 


ALUMINUM—A light malleable white metal. Speci 
fic Gravity 2 6. (A conductor of electricity.) 

AMALGAM—An alloy, part mercury. 

AMMETER—An instrument used to measure the 
flow of current, and connected in series in the 
circuit. 

AMPERE—The unit of current strength. 

AMPERE HOUR—The quantity of electricity passed 
by a current of one ampere in one hour; 

One ampere flowing for one hour; 

Two amperes flowing for one half hour; 

One half ampere flowing for two hours, all equal 
one ampere hour. 

AMPLIFIER—An instrument to increase the volume 
of a receiving signal. There are a number of dif¬ 
ferent types on the market such as vacuum-tube, 
magnetic, etc. 



Adjustable Rheostat 


ANCHOR BOLTS—Bolts used to fasten machines 
to their foundation. 

ANCHOR GAP—A spark gap used to disconnect the 
detector when using the transmitter. 

ANEMOMETER—A meter for measuring the direc¬ 
tion and velocity of the wind. 

ANEROID BAROMETER—An instrument for 

measuring atmospheric pressure. 

ANGLE OF DECLINATION—Variation of a com¬ 
pass; the angle of error of the magnetic compass. 

ANGULAR VELOCITY—The speed of a revolving 
or turning body. 

ANNULAR—Having the form of a ring; ring shaped. 

ANODE—Positive terminal of a conducting current. 


6 



\ ANTENNA—A receiving aerial. 

ANTI-FRICTION METAL—A tin, lead alloy like 
Babbit Metal. 

ANTI-INDUCTION CONDUCTOR—A conductor so 
made that it avoids induction effects. 

ANTI-SPARK DISCS—Discs made of Ebonite used 
to assist in preventing sparking on Bradfield tube. 

APERIODIC—Not tuned. 

APERATURE—An opening of any description in a 
partition. 

ARC—The arc between the two carbon electrodes 
slightly separated. 

ARC RECTIFIER—An apparatus used to change 
Alternating Current to Direct Current. 

AREOMETER—An instrument for finding the specific 
gravity of a fluid. 

ARMATURE—A collection of pieces of iron designed 
to be acted on by a magnet; a part of a generator. 

ARMATURE BORE-—The space within which the 
the armature revolves. 

ARMATURE COILS—The wires wound on the core 
of the armature. 

ARMOR CABLE—Wire enclosed in a metal pro¬ 
tective covering. 

ARTIFICIAL MAGNET—A piece of iron or steel 
that has been magnetized. 

ASBESTOS—A fibrous variety of ferro-magnesium 
silicate. A non conductor of heat, and fireproof. 

ASBESTOS COVERED WIRE—A cable of very 
fine strands of copper wire all twisted together and 
covered with an asbestos covering. 

ATMOSPHERE—Air, a mixture of. gases. 

' ATOM—The smallest division of a substance.. 

ATTENUATE—To make thin; to lessen the force of. 

AUDION—A relay operated by electrostatic control 
of currents flowing across a gaseous medium; con¬ 
sists of a heated filament, a grid electrode and a 
metal plate all enclosed in a highly evacuated bulb. 

ANDIOMETER—A meter for measuring the strength 

of incoming signals. 

AURORIA BOREALIS—A luminous display and 
electrical phenomenon seen in the heavens in the 
northern hemisphere. 

AUTO M ATI C—Self-acting. 

AUTOMATIC TRANSMITTER —A transmitter 
operated by running a paper tape between small 
metal wheels. 


7 


' AUTOMATIC TRANSFORMER—A transformer 

provided with one coil instead of two, part of the 
coil being traversed by the primary, and part by the 
secondary current. 

V AUXILIARY ANODE—The third element of the 

amplifier. 

A. W. G.—American Wire Gauge. 

B. A.—British Association. 

B. and S. W. G.—Brown and Sharpe Wire Gauge. 



Adjustable Load Coil 


B. W. G.—Birmingham Wire Gauge. 

B. X.—Metal tubing cantaining twin conductors each 
insulated from the other and both wires wrapped 
so as to completely fill the tubing. 

BABBIT METAL—An anti-friction metal. 

BALANCE, ELECTRIC—Wheatstone bridge. 

BALANCING SET—A dynamo used in a three wire 
system to balance the electromotive force. 

BALANCE WHEEL—A fly wheel; a wheel added 
to machines to prevent too sudden variations in 
speed. 

BALL AND SOCKET JOINT—A joint in which 
spherical object is placed within a socket made to 
fit it. 

BALL BEARING—A bearing whose journal works 
upon a number of metal balls and thus reduces 
friction. 

BALLISTICS—The science dealing with the velocity, 
path and impact of projectiles. 

BALLISTIC GALVANOMETER—A galvanometer 
used for measuring short duration currents. Used 
for measuring a condenser discharge. 

BAR MAGNET—A straight bar of steel with both 
ends magnetized. 

BAROMETER—A meter for measuring the pressure 
of the atmosphere. 


8 




BARS, COMMUTATOR—The bars of copper or 
bronze, making up the segments of a commutator 
of a dynamo or motor. 

BARRETTER—A thermal detector. 

BASE PLATE—The plate used as a foundation. 

\ BATTERY—A combination of elements for the pro- 
duction of storage of electrical energy. 

BATTERY, DRY—An open circuit battery containing 
solified zinc oxychloride of gelatinous silica. 

BATTERY GAUGE—A small galvanometer for test¬ 
ing batteries and connections. 

BEARING—The support on which the moving part 
of a machine rests. 

BEARING SURFACE—The surface of bearing part# 
which are in mutual contact. 

BEAUMES HYDROMETER—A hydrometer named 
after its maker; used to measure liquids lighter 
than water. 

BED PIECE—The frame carying a dynamo or motor 

BERNE BUREAU—Bureau of the International 
Telegraph Union at Berne, Switzerland. 



Basketball Vario-Coupler 


BICHROMATE CELL—Two carbon plates immersed 
in a solution of sulphuric acid, bichromate of potasfe 
and water. 

BIFURCATION—Spreading into two branches. 

BILLI CONDENSER—A variable tubular condenser. 

BINDING POSTS—Metal fixtures fitted to receive 
the ends of wires and thus make electrical contact 


9 


BISMUTH—One of the elements that is a conductor 
of electricity. 

BOARD OF TRADE UNIT—An English standard, 
1,000 watt hours, equal to one and one-third horse 
power; written B. O. T. 

BLIND FLANGE—A plate used to cover an orifice. 

BLUE STONE—Crystallized copper sulphate. 

BOLOMETER—An apparatus similar to Wheatstone 
Bridge. 

BORE—The interior diameter of a cylinder. 

BOOSTER—A dynamo used to raise the pressure 
of another dynamo. 

BRADFIELD INSULATOR—A leading-in insula¬ 
tor: an ebonite tube fittted with ebonite spark 
discs made to prevent rain running down and 
making a ground connection. 

BRASS—An alloy of seven parts copper and three 
parts zinc. 

BRAZING^—The process of joining metals together. 

BRAZING METAL—An alloy of tin and zinc. 

BREAKER—A switch or other device for opening 
a circuit. 

BRONZE—An alloy of copper, tin and lead. 



Variometer Units 1 


BROWN AND SHARPE GAUGE—A wire gauge of 
American standard. 

X BRUSH—A rod of carbon held in a holder and 
pressed against the commutator. 

s BRUSH HOLDER—An adjustable clamp into which 
the brushes are fixed and then held against the 
commutator. 

BRUSH, WIRE—A brush made of rolled wire gauze. 

B. T. U.—British Thermal Unit. 


10 


BUFFING WHEEL—A wheel covered with leather 
and mounted so it can be rotated; used for polish¬ 
ing. 

BUS BAR—A heavy copper conductor used on dis¬ 
tribution boards. 

B. W. G.—Birmingham Wire Gauge. 

CABLE—A heavy electrical conductor highly in¬ 
sulated. 



Showing Correct Method of Setting Brushes 

CALL BELL—A bell used to attract the attention 
of the person called. 

CAM—A revolving disc rotated on a shaft or 
spindle and shaped to give a variable motion to a 
driven element. 

CAM FRICTION—The friction between the cam and 
the element it actuates. 

CANADA BALSAM—A gum used in cementing 
lenses. Obtained from balsam fir. 

CAPACITY—The extent of space; power of contain¬ 
ing. 

CARRYING CAPACITY—The capacity of an elec¬ 
trical conductor to carry current without over¬ 
heating. 

CARBON—One of the elements; exists in three 
forms,—charcoal, graphite and diamond. It is used 
as an electrical conductor, for arc Lamps and in¬ 
candescent lamp filaments. The carbons used for 
arc lamps generally have a core of soft powdered 
carbon. 


11 







CARBORUNDUM—An artificial silicate of carbon 
produced under very high temperature; often used 
as crystal detector. 

CARTRIDGE FUSE—A safety device; fuse wire en¬ 
closed in a cardboard tube with metal ends. 

CASCADE—A number of Leyden jars connected in 
series. 

CATHODE—The terminal of an electrical circuit. 

CAT WHISKER—The fine wire used on a crystal 
detector. 

CENTIGRADE—A thermometer scale; freezing point 
0 ° ; boiling point 100°. 

CENTIMETER—Unit of length, 0.3937 inch. 

CENTRAL STATION—A point from which current 
is sent out. 

CENTRIFUGAL FORCE—The force which draws a 
body constrained to move in a circular path, away 
from the centre of rotation. 



Flexible Armored Cable. Twin Conductors 


CHARACTERISTICS OF SOUND—A, pitch; b, 
loudness; c, quality. 

CHARGE—A quantity of electricity at rest, measured 
by units of quantity such as the coulomb. 

CHECK UNIT—Generally called lock nut, a nut 
placed over another nut on the same bolt to lock 
the main nut in place. 

CHLORIDE—A non-inflammable gas, Atomic weight 
34 . 90 . Specific Gravity 1 . 4 . 

CHOKE COILS—Coils of wire wound on an iron 
core sometimes called induction coils. 

CHRONOSCOPE—An instrument for measuring very 
short intervals of time. 

CIRCUIT—The path through which the current 
flows. 

CIRCUIT-BREAKER, AUTOMATIC —A device 
a c.rcuit. 

CIRCUIT, CLOSED—A circuit closed so as to give 
the current a continuous path. 

CIRCUIT, OPEN—A circuit with its continuity 
broken, as by the opening of a switch. 


12 


v CIRCUIT-BREAKER, AUTOMATIC—A device 

that automatically breaks the circuit in case of 
overload. 

s CIRCUIT, GROUNDED—A circuit where the re¬ 
turn wire is done away with so that the earth 
completes the circuit, as in wireless work. 

CIRCULAR MIL—Unit of area, the area of a circle 
whose diameter is one mil. 

CLEAT—A wood, porcelain or composition support 
for wires. 

CLOCKWISE—A machine or other device that 
runs in a right hand direction; that travels as do 
the hands of a clock. 

CLOTH WHEEL—A polishing wheel. 

CLUTCH—A device for engaging or disengaging two 
pieces of shafting. 

CODE, CIPHER—A code of prearranged words, 
letters or signs. 

CODE, TELEGRAPHIC—An alphabet made up of 
dots and dashes. 

^ COIL—A series of rings or turns of wire, 
x COIL, INDUCTION—Built the same as a trans¬ 
former; has a laminated iron core and a primary 
and secondary coil. 

COIL, RESISTANCE—A coil of some poor conduct¬ 
ing metal wire such as German silver. Used to 
offer resistance to the flow of current. A rheostat. 

COINCIDE—Two or more articles that occupy the 
same place in space. 

COLLET—A metal ring used to retain metallic pack¬ 
ing in a stuffing box. 

COMMUTATOR—That part of a dynamo which 
changes the direction of the current. 

COMPASS, RADIO—An apparatus used to find the 
location of a radio transmitting or broadcasting 
station. 

COMPOUND—A mixture of two or more elements. 

COMPOUND WOUND GENERATOR—A dyilfomo 
giving a constant electromotive force, on account 
of having its field magnet winding partly in shunt 
with current generated. 

COUNTER CLOCK WISE—A machine that runs 
from right to left, the opposite direction to the hands 
of a clock. 

\ CONDENSER—An appliance for storing up electrical 
energy, made of a number of thin sheets of tin foil 
laid on top of each other and separated from each 
other by an insulator. Condensers in multiple 
will increase the total capacity. Condensers in 
series will decrease total capacity. 


13 


CONDENSER, ADJUSTABLE—A condenser, part 
of which may be cut in or out of the circuit, thus 
varying its capacity. 

CONDUCTANCE—The conducting property of any 
material. 

CONDUCTOR—Anything that will permit the pas¬ 
sage of electricity—a wire. 



Plug Fuse 


CONDUCTIVITY — The reciprocal of the ohm. Unit 
is the Mho, (Ohm written backwards). 

\ CONDUIT—A metal pipe through which electrical 
conductors are run. 

CONTACT, ELECTRIC—A contact between two 
conductors giving a continuous path for the current. 

CONTACT BREAKER — Any appliance for quickly 
opening or closing a circuit. 

CONSTANT LOAD — A load whose pressure is steady 
and invariable. 

CONTINUOUS — Uninterrupted, without break or in¬ 
terruption. 

' CONTINUOUS CURRENT—Direct current. A 
current that always runs in the same direction. 
The opposite to alternating current. 

CONTINUOUS WAVES—Waves whose amplitude 
are constant. Waves produced by frequency multi¬ 
plying transformers. 

CONVERTER—An electric machine or apparatus for 
changing the potential difference of an electrical 
current. 

COPPER—A metal; one of the elements; a good 
conductor of electricity. 

CORE—The iron centre of a transformer, on which 
the primary and secondary coils are wound. 

CORE DISCS—Thin metal discs used in building 
up armature cores, etc. 

COTTER PIN—A headless split pin. 

COUPLING WAVES—The two waves produced by 
coupling the oscillating circuits. 


14 


CORROSION —Chemical action which causes destruc 
tion of metals, usually by oxidation or rusting. 

\ CORRUGATED —Formed with a surface consisting 
of alternate valleys and ridges. 

\COULOMB —The practical unit of quantity of elec¬ 
tricity. It is the quantity passed by a current 
of one ampere intensity in one second. 

\ COUPLING —The connection of two oscillating cir¬ 
cuits. 

CRATER — The depression that forms in the positive 
carbon of a voltaic arc. 

C. P. —Abbreviation for Candle Power. 

CRYTAL DETECTOR —A detector using a crystal 
and thin metal wire to rectify a number of oscilla¬ 
tions. 

CURRENT — A current of electricity is supposed to 
flow from the positive pole of a generator, through 
the various appliances in the circuit and back to the 
generator through the negative pole. The unit of 
current strength is the ampere. 



Condenser 


CURRENT, DIRECT—A current that always flows 
in the same direction. The opposite to Alternating 
Current. « 

CURRENT, ALTERNATING—A current that is 
continually changing both its strength and direction. 
A current that changes its flow of direction so many 
times a second according to the construction of the 
alternator. These changes are called cycles. 
CURRENT FREQUENCY—The number of times 
alternating current changes its flow of direction in 
a second. These changes are called cycles. 


15 



CURRENT, INDUCED—A current produced in a 
conductor by induction. 

CURRENT, NEGATIVE—The current which deflects 
the needle to the left in a single needle telegraph 
system. 

CURRENT, POSITIVE—The current which deflects 
the needle to the right in a single needle telegraph 
system. 

CURRENT REVERSER—Some appliance, generally 
a switch for changing the direction of a current in 
a conductor. 

CUT-OUT—Either a fuse or a magnetic control ar¬ 
ranged to open a circuit should the circuit be over¬ 
loaded. 

CURRENT, SECONDARY—The current induced in 
the secondary coil of a transformer or induction 
coil. 

CYCLE—A term given to the alternation of an alter¬ 
nating current circuit. 

DASH COIL—An induction coil for jump spark 
ignition. 

DAMPING—The weakening of amplitude in a 
train of electro magnetic waves owing to resistance 
and radiation from an oscillating circuit. 

D. C.—Direct Current, (See “Current, Direct.”) 

DEAD BEAT—Where the moving indicator of measur¬ 
ing instruments comes to a reading quickly, with¬ 
out the indicator oscillating. 

DELTA GROUPING—A way of connecting up three 
phase windings in the form of a triangle. 

DETECTOR—An apparatus that changes tlte oscilla¬ 
tions received by the aerial into audible sounds. 

DETERIORATION—The state of growing worse. 

DEVIATION—Divergence from a course. 

DIAPHRAGM—A thin iron disc in the telephone 
receivers which is thrown into motion by electric 
impulses _ and changes the vibrations to audible 
sounds. 

DIELECTRIC—A non-conductor of electricty. 

DIFFRACTION—The bending of electro magnetic 
waves around the earth’s curvature. 

DIMMER—An adjustable choking coil used to 
regulate the intensity of electric incandescent lamps. 

DIRECT. CURRENT—A current of uniform strength 
that always flows in the same direction. 

DIRECTION The direction of an electric current 
ts supposed to be from the positive pole to the 
negative pole of the circuit. 


16 


\ DIRECT COUPLING—A coupling where the in¬ 
ductance coils of botn currents are directly con¬ 
nected. 

DIRECTION FINDER—See Radio Compass. 

DIRECTIVE AERIAL—See Bellini Aerial. 

DIRECT LOOSE COUPLING—A coupling where 
two .inductance coils, though directly connected, are 
at a distance from each other, or a coupling where 
only a few turns are common to both circuits. 

DIRECT TIGHT COUPLING—A coupling where 
one circuit has its inductance formed by tapping 
off a number of turns from the coil actually em¬ 
ployed as inductance in the other circuit. Also 
called Direct Close Coupling. 



Motor Generator 


DISC CONDENSER—A variable condenser with its 
two sets of plates composed of semi-circular inter- 
leafing metal vanes, separated by insulating discs 
or air; the whole being mounted in a circular case, 
one set of vanes is fixed, the other mounted on an 
insulated spindle is capable of being turned through 
an angle of ISO degrees, thereby permitting of any 
desired amount of interleafirig of vanes; thus regu¬ 
lating the amount of capacity. 

DISCHARGE—To dissipate electric energy from a 
condenser or battery. 

DISTANCE SPARKING—The distance between elec¬ 
trodes which a spark from some source will jump. 

DISTRIBUTION BOX—A metal box or cabinet 
containing a distribution panel together with fuses, 
switches, etc. 

DOUBLE POLE SWITCH—A switch with two 
knife like blades, able to break both the positive and 
negative wires of a circuit. 

DOWNLEAD—The wire connecting the aerial to 
the instruments. 


17 


DRY CELL—An enclosed battery used for open 
circuit work. 

DUPLEX—Twofold, working two ways. 

DYNAMICS—The mechanics of moving forces or 
motion, the reverse of static. 

DYNAMO—A machine used to convert mechanical 
energy into electrical energy. 

DYNOMETER—A meter for measuring mechanical 
force. 

DYNE—Unit of force. 

EARTH—Generally refers to a connection to the 
earth. An accidental grounding of a conductor. 

EBONITE—Vulcanized India rubber; a non-conduc¬ 
tor of heat and electricity. 

ECONOMIZER—A step-down transformer. 

EFFICIENCY, MECHANICAL—The rate between 
the work performed and the energy expended by 
the machine in performing it. 



Copper Wire Measuring Gauge 


ELECTRICITY—An unknown power; a powerful 
physical agent which manifests itself mainly by at¬ 
traction and repulsion; also by luminous and heat¬ 
ing effects, by violent commotions, by chemical 
decompositions and many other phenomena. The 
word was first used by Dr. Gilbert in England dur¬ 
ing the Sixteenth Century. 

ELECTRICS—Certain substances’ can be electrified 
by friction. 


18 


ELECTRODE—The terminal of an open electric 
v circuit. 

ELECTRODYNAMICS—Electricity in motion. 

ELECTROLYSIS—The breaking up of a compound 
into its elements by the use of an electric current. 

ELECTRIC HORSE POWER —746 watts are equal 
to one unit of Electric Horse Power. 

ELECTROLYTIC DETECTOR—A fine wire making 
contact with an electric light. 



Vario-Coupler 


ELECTRO MAGNET—A mass of iron magnetized 
by winding around it several coils of copper wire. 
The softer the iron the more easy it is to magnetize. 
Hard metals retain their magnetism longer. 

ELECTRO MOTIVE FORCE—Another term foj 
electric pressure or voltage. 

ELECTROSCOPE—Apparatus for detecting static 
charges of current. 

' ELEMENT—There are ' about seventy-five known 
elements. Is an original form of matter that can¬ 
not be divided into constituents by any process. 

EMBOSSER, TELEGRAPH—A receiver which em 
bosses telegraphic paper tape. 

EMERGENCY APPARATUS—A second generator 
set that can be used in case of trouble. 

EMERY WHEEL—A machine used for grinding. 

E. M. F.—Electro Motive Force. Voltage. Pressure. 

ENERGY—Capacity of acting; energy may be 
mechanical, electrical, chemical, physical, etc. Unit 
of energy is the ERG. 

ENERGY, ELECTRIC—Unit is the volt coulomb 
or volt ampere. 

EQUIDISTANT—Placed at equal distance from the 
same point. 

EQUIVALENT, ELECTRO - CHEMICAL — T h e 

weight of a substance set free by one coulomb of 
electricity. 


19 


SRG.—The unit of work. The amount of energy 
expended in moving a body through one centimeter 
against a resistance of one dyne. 

y ETHER—A name given by Huygens to the medium 
that fills all space and matter. 

EXCITER—A dynamo used to excite the fields of 
a generator. 

FAHRENHEIT—A thermometer scale. Freezing 
point is 32 °. Boiling point, 212 °. 

FATHOM—A measure of length; six feet. 

FARAD—Practical unit of capacity. 

FEEBLY DAMPTED—A train of oscillations with 
many complete oscillatory motions. 

FEEDER—A main wire or set of wires. 

FEEDER, POSITIVE—-The wire connected to the 
positive pole of a generator. 

FEEDER, NEGATIVE—The wire connected to the 
negative pole of a generator. 

FEEDER, NEUTRAL—The wire connected 'to the 
middle or neutral point in a three-wire systefri. The 
wire common to both generators. 



FIELD MAGNETS—Electric magnets that produce 
the magnetic field in which the armature of a gen¬ 
erator rotates. 

FIELD REGULATOR—A variable resistance. 

FLATS—Commutator segments worn to a lower level 
than other segments. 

FLAT TUNING—The considerable adjusting of tun¬ 
ing without altering the strength of the signals. 

FLUX—A compound used in soldering. 

FOOT POUND—The resistance equal to one poum 
moved upwards one foot. 

FORCE—May be defined as the rate of change 
of momentum. 

FREAK—The increasing or decreasing of range of 
signals that periodically happens to a receiving set. 

FREQUENCIES, RADIO—Radio frequencies are 
very high, sometimes as high as l,oOO,OUO cycles per 
second. 

\ FUNDAMENTAL WAVELENGTH—Ordinary wave¬ 
length of a circuit. 


20 









FUSE—A short length of fusable wire introduced into 
a circuit as a safety device. 

FUSING POINT—The temperature at which metals 
melt and become liquid. 

GALENA—A crystal sulphide of lead. When heated 
becomes lead sulphate. Used as a thermo-electric 
detector. 

GALVANIZED IRON—Iron with a coating of zinc 
to prevent rusting. 

\ GALVANOMETER—An instrument for measuring 
current strength and direction of current in a 
circuit. 

GAP—An opening by breaking or parting. 

GAP MICROMETER—A gap to protect apparatus 
from overloads. 

GASKET—A ring or washer used for packing or 
insulating. 

GAUGE—An instrument to measure size or capacity. 

GAUZE WIRE—A pliable wire cloth made of very 
fine .strands of wire. 

GEISSLER TUBE—A vacuum tube having its elec¬ 
trodes in bulbs. 

GENERATOR—An apparatus for maintaining an 
electric circuit. 

GERMAN SILVER—Alloy of nickel and copper with 
a percentage of zinc. Used in resistance frames, 
rheostats, etc. 

GOLD—One of the elements; a conductor of elec¬ 
tricity. 

GONIOMETER—An instrument for measuring angles. 

GRAM—The unit of weight. Equal to 15.43 grains. 

GRAPHIC TELLURIUM—A crystal rectifier. 

GRAPHITE—A soft form of carbon, used as a lubri¬ 
cant. 

GRAVITY—The attracitve force of the earth. 

% GRID.—A frame of wire gauze found between the 
plate and filament o/ a vacuum tube. Perforated 
f lead plate used in storage batteries. 

GRID LEAK—A form of rheostat to permit excess 
grid charges to escape to an external source. 

GROUND—The contact of an electrical conductor 
with the ground or with some other conductor not 
in the circuit. 

GROUND CLAMP—A strip of copper for making 
an easy and secure connection with a water pipe, etc. 

GROUND WIRE—The wire leading from the aerial 
'to the ground. The wire used as a return wire of 
the circuit in wireless work. 


:i 


GUN METAL—A compound of nine parts copper 
and one part tin. 

GUTTA PERCHA—The hardened juice of the Isom 
andra Gutta, used as an insulator. 

GUY ROPES—Ropes or wires used to steady the 
aerial supports. 

HAND OR WING NUT—A nut with flanges allow¬ 
ing it to be tightened by hand. 

HEAT—A physical kinetic form of energy. 

HELIOGRAPH—A mirror for reflecting flashes of 
light, generally the Sun’s rays; used in signal work. 

HELIX—A coil of wire. 

HENRY—Unit of inductance. 

HEITZIAN WAVES—Ether waves. 

HIGH FREQUENCY—A current with a very great 
number of alternations per second. 

HIGH FREQUENCY SLIDING INDUCTANCE— 

Two metal bars connected by a sliding brass clamp 
used for making final adjustment in closed oscilla¬ 
tory circuits. 

HIGHLY DAMPED TRAIN—A train with few 
oscillations. 

HONEY-COMB COIL—A tuning coil. A set of 
three coils—primary, secondary and tickler; the 
primary coil being placed between the other two. 

HORSE POWER—A unit of rate of work. Equal to 
the raising of 3o,f)00 pounds one foot in one minute. 
Equal to 740 watts. 

HORSE POWER HOUR—One horse power exerted 
for one hour. 



Grid Leak 


HORSE SHOE MAGNET— A steel bar shaped like 
a horse shoe with its ends magnetized. 

HUMIDITY—The dampness in the atmosphere which 
varies with the temperature. 

HYDROELECTRIC GENERATOR—A generator 
driven by a turbine. 

HYDROMETER—An instrument used to test the 
specific gravity of a fluid. Used for testing the 
discharge of storage batteries. 

HYPOTHESIS—Taken for granted. Assumed for 
the purpose of argument. 


22 



HYSTERESIS—A reluctance when a change of con¬ 
dition is taking place in a circuit. 

IMPEDANCE—The total opposition of a circuit, 
due to reactance and resistance to a varying circuit. 

IMPEDANCE COIL—Another name for induction 
coil, an iron core around which is wound a coil of 
wire. 



Resistance Coils, Connected in Series 
With Each Other 


INCANDESCENCE, ELECTRIC—The heating of a 
conductor to a white heat. 

INCH—The twelfth part of a foot. A measure of 
length. 

INCLINATION—A tendency from the true horizon¬ 
tal or vertical direction, as in the case of the compass 
needle. 

INDUCTION COIL—A transformer; an apparatus 
for changing low voltage to high voltage. 

INDUCTANCE—The induction of a current in a non¬ 
electrical body from an electrified or magnetized 
body, without metallic or electrical connection. 

INDUCTOR—A step-down transformer. 

INDUCTIVE COUPLING—The coupling of two 
oscillatory circuits by arranging the inductance coil 
of one circuit into the lines of force of the other 
circuit. 

INDUCTIVE LOOSE COUPLING—A coupling 
without metallic contact and where the inductances 
are well apart. 


23 





INERTIA—Property of matter at rest. 

INSULATOR—Any material that will not allow the 
passage of electricity through it, except under very 
great pressure. 

INSULATING TAPE—A prepared tape to cover 
and insulate ends of wires when making joints, etc. 

INTENSITY The strength of a current, expressed 
in amperes. 

INTERMITTENT—Acting at intervals. 

INTERSECTION—The place where two wires cross 
each other. 

IRON A metal; one of the elements. 

INTERFERENCE—-Where more than one set of 
electro magnetic waves arrive in such a manner as 
to nullify each other. 



Variable Condenser 


INVERTED "L” AERIAL—An aerial that is tapped 
at one end by the lead in wire. 

JAMMING QRM. Interference from other stations. 

JIGGER—An oscillation transformer. 

JOULES—Unit of electrical work. Volt coulomb. 

JO r^?f?c AL_ 7v rh t t part of a shaft or spindle which 
rotates in the bearings. 

KBY TRANSMITTER-An easily controlled switch 
wh’ch allows the operator to rapidly make and 
break the primary circuit. 

KILOWATT One thousand watts. Written K. W. 


24 







KNIFE SWITCH—A switch with knife like blades, 
used on circuits carrying high amperage. 

LAG SCREW—A wood screw with a square head. 

LAMINATED—Made up of a number of fine sheets. 

LATERAL FORCE—Force proceeding from the side. 

LAW OF MAGNETISM,—Like poles repel one an¬ 
other. Unlike poles attract each other; positive 
pole attracts negative, etc. 

LEADING-IN INSULATOR—An insulation tube 
used in the walls or roof through which the lead 
in wire from aerial runs. 

LEAKAGE—A loss of current due to poor insula¬ 
tion or other causes. 



Synchronous Gap Motor 


LENZ LAW—An induced current always tends to 
stop the current which produces it. 

LEYDEN JAR—A static condenser. 

LIGHT—Light waves travel at the same rate of 
speed as electro magnetic waves; 186,000 miles 

per second. Light is merely ether vibrations. 

LIGHTING ROD—A metal rod connected with the 
earth, used on buildings as a safety device. 

LINES OF FORCE—Imaginary lines showing the 
direction of attraction and repulsion in a field of 
force. 

LINK FUSES—A link of fusable metal, introduced 
into the circuit as a protective device. 


25 



LOADING COIL—A single slide, tuning coil. 

LOCAL CURRENTS—Currents within the metal 
parts of a generator. 

LOCK NUT—A nut placed over another nut on 
the same bolt to hold the original nut in place. 
A check nut. 

LODESTONE—An iron ore which possess the prop¬ 
erties of a magnet. Also known as Magnetite. 

LOG DECREMENT—The hyperbolic log of recipro¬ 
cal of the ratio of the first amplitude to second 
amplitude in a train of waves. 

LOOSE COUPLING—A coupling without metallic 
contact or where the inductances are well apart. 

LOST MOTION—The motion in a machine that 
produces no useful results. 

LOW FREQUENCY—A current whose alternations 
are low per second. 



AMMETER CONNECTED IN SERIES 

\ 

LOOP AERIAL—A frame around which several turns 
of wire are wound. 

LUBRICANT—Anything used to help diminish fric¬ 
tion between two or more working parts; like oil; 
graphite, etc. 

LUGS—Metal wire terminals 

MAGNET—A piece of iron or steel that has the 
property to attract or repel other pieces of metal. 

MAGNET COIL—The coil over an iron core in an 
electric magnet. 

MAGNETIC FIELD—The field or space over which 
the magnet exerts its influence. 

MAGNETIC FLUX—The lines of force which flow 
from a magnet; magnetic induction. 

MAGNETIC FORCE—Force at any point in a 
magnetic field. 

MAGNET HORSESHOE—A bar of steel shaped 
like a horseshoe with both ends magnetized. 


2 6 








MAGNETIC LIMIT—The temperature beyond which 
a metal cannot be magnetized. 

MAGNETIC SELF INDUCTION—A magnet tends 
to repel its own magnetism and weaken itself by 
self-induction. 

MAGNETITE—A natural magnetic iron ore. Lode- 
stone. 

MAGNETO—A small generator. 

MAKE AND BREAK CURRENT—A current con¬ 
tinually broken and started again as is the action 
in an induction coil. 

MALLEABLE—Capable of being worked into shape. 

MANGANESE BRONZE—An alloy of copper, tin 
and ferromaganese ore. 

MANGANESE STEEL—An alloy of steel and metal 
manganese. 

MARCONI FILINGS COHERER—A glass tube 
containing fine metallic filings used as a detector. 

MEGAPHONE—An instrument used to help make 
the voice audible at a distance. 

MEGOHM—One million ohms. 



Adjustable Filament Rheostat 


MERCURY—A metallic element liquid at ordinary 
temperature; also known as quicksilver. 

METER VOLT—An instrument for measuring the 
pressure or voltage of a. circuit. Connected in mul- 
tiple on your line. 

METER AMPERE—An instrument for measuring the 
flow of current. 


27 


METER WATT—An instrument for measuring the 
wattage. Volts times amperes. 

MHO—Unit of Conductivity. The word ohm spelled 
backwards. 

MICA—A mineral more or less transparent and used 
as an insulator. 

MICANITE—A manufactured insulator made of mica, 

MICRO—One millionth. 

MICROFARAD—Unit of capacity. 

MICROHM—One millionth of an ohm. 

MICROMETER—An instrument for measuring small 
distances like the thousandth or ten thousandth part 
of an inch. 

MICROMETER SPARK GAP—An adjustable spark 
gap used in the aerial circuit. 

MICROPHONE—An apparatus to magnify sound. 

MIL CIRCULAR—A unit of area. The area of a 
circle whose diameter is one mil. 

MIL FOOT—A unit of resistance. A wire one foot 
long with a diameter of one mil. 

MILLIMETER—A unit of length. One thousandth 
part of a meter. 

MINIMUM—The least quantity. 

MOLECULE—The smallest part of an element that 
can exist alone. 

MOLYBDENITE.—A sulphide of Molybdenum. Used 
as a detector. 

MORSE RECEIVER—A receiver named after S. F. 
B. Morse. 

MORSE INKER—An instrument that records the 
received message on a travelling paper tape. 

MOSCISKI CONDENSER—A condenser in the form 
of a glass tube with a metal foil coating. 


MOTOR—A machine to convert electrical energy 
into mechanical energy. 

MOTOR GENERATOR—A combined motor and 
generator; a generator driven by a motor. 

MOTOR SERIES—A motor whose armature wind¬ 
ings and field windings are in series. 

MULTIPLE—Multiple connection is that in which 
each lamp draws its supply direct from the mains 
and is not depending on any other lamp or set 
of lamps for its supply. Lamps in parallel with 
each other. The opposite to series. 

\ MUTUAL INDUCTION—The introduction of an 
electrical pressure in a circuit, by another circuit 
not directly connected to it. 


28 






NATURAL CURRENTS—Earth currents. 

NATURAL WAVELENGTH—The natural length of 
wave produced by the aerial’s own capacity and 
inductance. 

NEGATIVE—The opposite to positive. The pole to 
which the current seems to flow. 

NEGATIVE CHARGE—One of the two electric 
charges, the opposite to positive. 

NEUTRAL WIRE—The middle wire of a three wire 
system. t The wire that is common to both dynamos. 

NICKEL SILVER—An alloy of nickel, copper and 
zinc. German silver used in making resistance coils. 



Basketball Variometer 


NICKEL STEEL—Steel with the addition of a small 
percentage of nickel. 

NON-CONDUCTOR—Any material that will nor 
'conduct electricity. 

NON-INDUCTIVE CIRCUIT—A circuit possess 
ing a very small inductance. 

NOTCH WIRE GAUGE—A gauge with notches foT 
measuring wire. 

OHM.—Unit of electrical resistance. The resistance 
offered by a column of pure mercury, 106.3 centi¬ 
meters in length by one square millimeter in cross 
section at a temperature of zero centigrade. 

OHM’S LAW—The fundamental principle on which 
all electrical mathematics are worked. The current 
in amperes is equal to the voltage divided by the 
resistance in ohms. The resistance is equal to the 
voltage divided by the current in amperes. The 
voltage is equal to the resistance in ohms times 
current in amperes. Thus with two known quan¬ 
tities you can always find the third unknown. 


29 




OHMIC RESISTANCE—True resistance. 

OSCILLATING CURRENT—An alternating current 
of high frequency. 

OSCILLATOR HERTZIAN—A device for produc¬ 
ing oscillations. 

OSCILLATORY INDUCTION—Induction produced 
by action of an oscillatory discharge. 

PAPER CONDENSER—A condenser made with tin 
foil and paraffin paper. 

PARTITION INSULATOR—A leading-in insulator. 

PERIOD—Time required to produce and complete 
one wave: time required to complete one cycle of 
an alternating current circuit. 

PERIPHERY—The circumference of a circle. 



Radiotron Tube Socket 


PERMANENT MAGNET—A magnet that will re¬ 
tain its magnetism away from the source of magnet¬ 
ism. 

PHENOMENON—An unusual occurrence. 

PHONETRON—A trade name for a type of amplify¬ 
ing telephone receiver. Consists of an enclosed 
electro-magnetic solenoid producing an annular 
field in which an armature coil is suspended from 
the apex of a conical diaphragm. The magnet 
requires a current of amperes at a pressure of 
6 volts. 

PHOSPHOR BRONZE—A very hard alloy of copper, 
tin and phosphorus. 

PLUNGER—A movable core used with a solenoid 
to be drawn in an oil bath when the coil is excited. 

POLARIZATION—The changing of a voltaic cell 
by depriving it of its proper pressure. 

POLARITY—Pertaining to the poles of a circuit; 
the positive and negative. 

POLYPHASE—More than one phase. Multiphase. 


30 










POSITIVE POLE—The pole from which the cur¬ 
rent is supposed to start on its journey around the 
circuit. 

POTENTIAL—The pressure of an electric charge. 

POTENTIOMETER—An arrangement for determ¬ 
ining potential difference. 

POUNDAL—British unit of force. 

POWER—Activity; rate of doing work. 

PRIMARY COIL—The coil of a transformer that 
is connected to the source of supply. 

PRIMARY COLORS—Red, yellow, blue. 

PRIMARY POWERS—Water power; wind power; 
tide power; power of combustion; power of vital 
action. 

PRIMARY TUNING INDUCTANCE—A variable 
inductance in the primary closed oscillatory circuit. 

PROTECTIVE ROD—A carbon rod of high resist¬ 
ance connected into the circuit as a safety measure. 

PROPAGATION—The travelling of electro magnetic 
waves over the earth’s surface. 

PYROMETER—A meter for measuring excessive 
heat. 

QUADRANT—A quarter of a circle; an angle of 
90 degrees. 

QUARTZ—A hard rock of native silica. 

QUENCHED SPARK—A spark gap made of a series 
of metal plates insulated from each other. 

QUICKSILVER—Mercury; a liquid metal. 

RADIAL—Spreading from a centre. 

RADIATION — The transmission of ether waves 
through space. 

RADIATING CIRCUIT—The aerial circuit. 

RADIO TELEPHONY—Transmission of speech by 
electro magnetic waves. 

REACTION—Inverse action. 

REACTANCE—The opposition offered to the flow 
of current by back electro motive force, etc. 

REACTANCE COIL—An adjustable iron core 
around which is wound a coil of wire. 

RECTIFIER—An apparatus for changing alternating 
current to direct current. 

REFRACTION—The change in direction or bending 
of the electro magnetic waves. 

REGENERATIVE CIRCUIT—A reactionary circuit. 

RECEIVING DETECTOR—A device to change the 
characteristics of incoming oscillations so as to 
make them audible. 


31 




RECEIVING TUNER—An oscillation transformer 
which allows the operator to receive electro mag¬ 
netic waves of different lengths. 

RELAY—An instrument consisting of an electro¬ 
magnet which actuates upon receiving a current 
and in actuating opens and closes a circuit. 

RELUCTANCE—The resistance offered to the flow 
of lines of magnetic force. 

RESISTANCE—That property of an electrical con¬ 
ductor which tends to oppose the flow of current 
over it. Everything in a circuit offers resistance 
to the flow of current. 

RESISTANCE BOX—A box filled with resistance 
coils connected in series with each other; a resist¬ 
ance frame. 



Quenched Gap 


RESISTANCE, OHMIC—True resistance. 

RESISTANCE, SPURIOUS—Counter electric mo¬ 
tive force. 

RETARDATION—A retarding of the rate of trans 
mission of signals. 

RESONATOR—A sound box. 

RETENTIVITY—Coercive force. 

RHEOSTAT—An instrument used to offer resistance 
to the flow of current. Made of a number of metal 
coils (German silver or iron) connected together 
in series and mounted on a frame from which the 
coils are insulated. 

RHUMKORFF COIL—An induction coil. 

ROTARY—Turning on an axis—rotating. 


82 


RUBBER COVERED WIRE—A cable either solid 
or stranded with a rubber covering and an outer 
protective covering of cotton braid. 

SAL AMMONIAC—Ammonium chloride. 

V SECONDARY COIL—The coil of a transformer 
into which the current is induced. 

\ SERIES—An electrical connection where lamps are 
connected so that they depend one on the other for 
supply, the current passing through each lamp suc¬ 
cessively. The opposite to multiple. 



\ 


\ 


SET COLLAR—A ring used on a shaft or spindle 
to prevent end play, 

SEXTANT—An instrument used on board ship to 
measure angles. 

SHEET METAL GAUGE—A gauge to measure the 
thickness of metals. 

SHELLAC—A gum gathered from trees in India 
used in radio and electrical work in the form of a 
varnish. An excellent insulator. 

SHORT CIRCUIT—Two wires of opposite polarity 
coming in contact with one another without any 
controlling device. 

SHUNT—A shunt for the receiving relay consisting 
of the coils of an electro magnet. 

SHUNT WINDING—A system of winding where 
the armature winding is in parallel with the field 
winding. 

SILICON—A mineral. Used as a detector. 

SIXTY CYCLE A. C.—This is when the current 
changes its flow of direction sixty times a second. 
This frequency is used a great deal for lighting 
and power purposes. 

SINGLE PHASE—Using only two wires and one 
electromotive force; sometimes called monophase. 

SLIDING FRICTION—The friction that exists be¬ 
tween moving parts in sliding contact with each 
other. 

SLIP RINGS—Two rings on an alternator that take 
the place of a commutator on a direct current 
dynamo. 

SOLENOID—An electro magnet without the iron 
core. 


SPARK COIL—An insulated wire wound around an 
iron core, used for producing a spark from a source 
of low pressure. 

SPARK GAP—The space between the ends of an 
electric resonator across which the spark jumps. 


33 




V 


SPECIFIC GRAVITY—The density of a solution 
against that of another, using water as a standard. 

SPECIFIC RESISTANCE—Resistance of any ma¬ 
terial having a cube of one centimeter. 

SPIRAL WINDING—The system of winding used 
on a ring armature. 

STAGE CABLE—A cable containing twin con¬ 
ductors each insulated from the other and the whole 
covered with a composition covering. 

STAND-BY—A position of tuning, allowing the re 
ception of waves of various lengths. QRX. 



RHEOSTAT 



RHEOSTAT 


® Q 



® 

\ 

o C 

\ 

O Ok 


\ 




rheostats in series 


STANDARD CELL—The Weston Cell is now used 
as the standard. 

STARTING BOX—An adjustable resistance to regu 
late the flow of current when starting up the motor. 

STATIC—Atmospheric disturbance. 

STATIC CHARGE—An electric charge at rest. 

STATIC LEAK—A coil of wire used in the aerial 
circuit of tuner to allow atmospherics to leak to 
earth. 

STATIC TRANSFORMER—A transformer withoui 
moving parts. 

STATOR—The stationary part of an induction motor 
or generator. 

STEEL—Iron hardened by the addition of carbon 
and managanese. 

STEP DOWN TRANSFORMER—A transformer 
that steps down the voltage and raises the amper- 
s&ejrjhns a greater number of turns of wire in prim¬ 
ary, than in secondary. 

STEP UP TRANSFORMER—A transformer that 
steps up the voltage and lowers the amperage; has 
a greater number of turns of wire in the secondary 
than in the primary. 


34 























STORAGE BATTERY—An accumulator. A number 
of cells for the storage of electricity. 

STORAGE CAPACITY—The number of ampere 
hours that can be got from a storage battery. 

SULPHATING—The formation of a lead sulphate 
in storage batteries. May be overcome by pro¬ 
longed charging. 

SULPHURIC ACID—A compound of sulphur, hydro¬ 
gen and oxygen. 

SWITCH—A device for opening or closing a circuit. 

SWITCH BOARD—A board to which the mains are 
led connecting with bus bars, fuses and switches. 

SWITCH, DOUBLE POLE—A heavy switch that 
disconnects or connects two leads simultaneously. 

SWITCH, KNIFE—A switch with knife like blades 
used on circuits carrying high amperage. 

SWITCH, SNAP—A small switch made to give a 
sharp break used on house lighting circuits, etc. 

SWITCH, THREE WAY—A switch so constructed 
that by turning its handle connection can be made 
from one lead to either of two other leads and also 
so that connection can be completely cut off. 

SYNCHRONOUS—Simultaneous; to correspond in 
time. 

SYNCHRONOUS MOTOR—A motor which runs in 
synchronism with the alternating current supply. 


c-\ 

s 

\ 

V -V 

rheostat 

® 

V r 

RHEOSTAT 

qS_ 9 l ] 


/ r 


_I_ J 


L.___—--——--' 


RHEOSTATS IN MULTIPLE 

"T” AERIAL—An aerial where the horizontal span 
is tapped in the middle by the lead in wire; thus 
forming a letter T. 

TELEFUNKEN—German name for radio telegraphy. 

TERMINAL LUGS—Metal terminals for ends of 
wire used so that good and quick connection can 
be made. 

TESLA COIL—An oscillating transformer. 

THERM—A unit of heat. 


35 


















THERMAL DETECTOR—A detector which acts by 
heat energy. 

TOGGLE JOINT—An elbow joint. 

THREE WIRE SYSTEM—A system of distribution 
of electrical current where three wires instead of 
two sets of two wires are used. The middle or 
neutral wire acts as a positive for the one side and 
of the system and as the negative for the other 
side. The advantage of the system is the saving 
of copper. 

TICKLER COIL—A coil in the circuit of a vacuum 
tube receiver to transfer a part of the oscillating 
plate current energy into the grid circuit to enable 
the vacuum tube to generate oscillations of high 
frequency. It is coupled to the secondary of the 
oscillation circuit. An inductance coil. 

TONE FREQUENCY—Spark frequency. 



Wavemeter 

TRANSFORMER—An apparatus used on an alter¬ 
nating current circuit to either raise or lower the 
voltage. Made of two coils of wire named the 
primary and the secondary coils and a laminated 
iron core. The coils are insulated from the core 
and from each other. The current enters the trans¬ 
former through the primary coil and sets up a 
magnetic flux around the core; the secondary coil 
cuts the lines of magnetic force and thus a new 
current is induced in the secondary. 


36 






TRANSFORMER COILS—The two coils in a trans¬ 
former ; primary and secondary. 

TRANSFORMER CORE—A core made up of thin 
iron plates laid one on top of the other. 

TRANSMITTER—An instrument used to produce 
sounds to be transmitted. 

TRANSVERTER—A trade name for a motor gener¬ 
ator. 

TUNING—The process of securing the maximum in¬ 
dication by adjusting the time period. 

TWO PHASE—An alternating current system of 
electrical distribution making use of two currents 
of different phase. Can be arranged with either 
three or four wires. 

UNIPOLAR DYNAMO—A dynamo where one part 
of the conductor slides around the magnet. 

ULTRAUDION—An audion used in a circuit having 
a type of energy coupling so that a powerful relay 
action may be obtained. Its elements are connected 
in two circuits so arranged that the energy coupling 
may be obtained through a bridging condenser in 
its plate filament circuit. 

VACUUM—A space destitute of all substance. 

VACUUM TUBE—The name given to the highly 
exhausted glass tube containing three elements. 
Used for detector in radio work. 

VARIO-COUPLER—A device for varying the in¬ 
ductance in a circuit. The primary and secondary 
coils are connected magnetically but not electrically. 

VARIOMETER—A device for varying the induc¬ 
tance in a circuit. Made by connecting two in¬ 
ductances in series. 

VARLEYS CONDENSER—A static condenser. 

VELOCITY—The rate of motion of a body. 

VIBRATION PERIOD—In electrical resonance the 
period of a vibration in an electrical circuit. 

VALVE AMPLIFIER—Audion type vacuum tube 
containing three electrodes. 

VALVE TUNER—A tuner used with a valve de¬ 
tector. 

VARIABLE CONDENSER—A condenser which al¬ 
lows of easy and quick adjustment. 

VOLTAGE—Electric motive force or pressure. 

VOLTMETER—An instrument used to measure the 
pressure of a circuit. 

VULCANITE—Vulcanized India rubber. 

WATT—The practical unit of electrical power. Am¬ 
peres times voltage. 


37 



\ 


One 


WATT HOUR—Watts times length in hours. 

watt expended for one hour. 

WATT MINUTE—One watt expended for one 
minute. 

WATT SECOND—One watt expended for one second. 
WAVE CHANGER—A transmitting switch to 

change from one wave length to another. 




WAVES, ELECTRO-MAGNETIC—Ether waves 

due to electro magnetic disturbances. 

WAVE LENGTH—The distance covered by a wave 
from the transmitting station before the next suc¬ 
cessive wave starts. 


WAVE TRAIN FREQUENCY—The total number 
of waves being produced or received per second. 

WAVE METER—An instrument to measure wave 
lengths. 

WIRE GAUGE—A gauge for measuring the dia¬ 
meter of wires. 


Centimeters to Inches 


cm. 


inches 

1 

zz 

H 

2 

zz 

it 

3 

zz 

1ft 

4 

zz 

1ft 

5 

zz 

Hi 

6 

zz 

2 x 

7 

zz 

2H 

8 

zz 

3ft 

9 

zz 

3ft 

10 

zz 

3 if 

11 

zz 

4ft 

12 

zz 

4 H 

13 

zz 

5 'A 

14 

zz 

5 y* 

15 

zz 

m 

16 

zz 

6 ft 

17 

zz 

6H 

18 

zz 

7 ft 

19 

zz 

IVi 

20 

= 

7^ 


The above values are 
correct to ft in. 


Inches to Millimeters 


Inches 

mm. 


cm. 

ft 

zz 

1,58 

— 

0,16 

v% 

zz 

3.17 

zz 

0,32 


— 

G.35 

zz 

0,63 

H 

— 

9,5 

zz 

0,95 

y 2 

— 

12.7 

zz 

1,27 

Vs 

zz 

15,9 

zz 

1,59 

H 

— 

19 

zz 

1,9 


— 

0‘> 2 

— 

2,2 

l 

— 

25,4 

— 

2,54 

2 

zz 

50.8 

zz 

5,08 

3 

zz 

76.2 

zz 

7,6 

4 

zz 

101,6 

zz 

10,1 

5 

— 

127 

zz 

12,7 

6 

— 

152 

— 

15,2 

7 

— 

177 

— 

17.7 

8 

— 

203 

— 

20.3 

9 

— 

229 

zz 

22.9 

10 

— 

254 

zz 

25,4 

11 

— 

280 

zz 

2S 

12 


304 

= 

30,4 


The above values are 
correct to Yi mm. 


38 





U. S. RADIO LAWS AND 
REGULATIONS 


The owner of an amateur radio transmit- 
;ing station must obtain a station license be- 
| fore it can be operated if the signals radiated 
! herefrom can be heard in another state; and 
[ also if such a station is of sufficient power 
i as to cause interference with neighboring 
I licensed stations in the receipt of signals from 
! transmitting stations outside the state. These 
I regulations cover the operation of radio-tele¬ 
phone stations as well as radio-telegraph 
I stations. 

Station licenses can be issued only to citizens 
of the United States, its territories and 
dependencies. 

Transmitting stations must be operated un¬ 
der the supervision of a person holding an 
Operator's License and the party in whose 
name the station is licensed is responsible for 
its activities. 

The Government licenses granted for ama¬ 
teur stations are divided into three classes 
as follows: 

Special Amateur Stations known as the “Z r 
class of stations are usually permitted to trans¬ 
mit on wave lengths up to approximately 375 
meters. 

General Amateur Stations which are per¬ 
mitted to use a power input of 1 kilowatt and 
which cannot use a wave length in excess 
of 200 meters. 

Restricted Amateur Stations are those lo¬ 
cated within five nautical miles of Naval radio 
stations, and are restricted to ^ kilowatt in- 


39 



put. These stations also cannot transmit on 
wave lengths in excess of 200 meters. 

Experimental stations, known as the “X” 
class, and school and university radio stations, 
known as the “Y” class, are usually allowed 
greater power and also allowed the use of 
longer wave lengths at the discretion of the 
Department of Commerce. 

All stations are required to use the minimum 
amount of power necessary to carry on suc¬ 
cessful communication. This means that while 
an amateur station is permitted to use, when 
the circumstances require, an input of 1 kilo^ 
watt, this input should be reduced or othj 
means provided for lowering the antenj ' 
energy when communicating with near-by st 
tions in which case full power is not require 

Malicious or wilful interference on the pa $ 
of any radio station, or the transmission i 
any false or fraudulent distress signal or csA 
is prohibited. Severe penalties are provide 
for violation of these provisions. 

Special amateur stations may be licensed I 
the discretion of the Secretary of Commeri 
to use a longer wave length and higher powC 
than general amateur stations. Applicants fer 
special amateur station licenses must have ha 
two years’ experience in actual radio con! 
munication. A special license will then t 
granted by the Secretary of Commerce on! 
if some substantial benefit to the science ci 
radio communication or to commerce seen* 
probable. Special amateur station licenses art] 
not issued where individual amusement is th 
chief reason for which the application is madtj 
Special amateur stations located on or nea 
the sea coast must be operated by a perso 
holding a commercial license. Amateur statio 
licenses are issued to clubs if they are inj 
corporated, or if any member holding an amal 
fa,it- Anprofnr’c lirpncp will nerent the reSDOn 


teur operator’s license will accept the respon 
sibility for the operation of the apparatus. 


40 




Applications for operator's and station 
licenses of all classes should be addressed to 
the Radio Inspector of the district in which 
the applicant or station is located. Radio 
Inspectors' offices are located at the following 
places: 


First District.Boston, Mass. 

Second District.New York City. 

Third District.Baltimore, Md. 

Fourth District..Norfolk, Va. 

Fifth District..New Orleans, La. 

Sixth District..San Francisco, Cal. 

Seventh District.Seattle, Wash. 

Eighth District.Detroit, Mich. 

Ninth District..Chicago, Ill. 

No license is required for the operation of 
a receiving station, but all persons are required 
by law to maintain secrecy in regard to any 
messages which may be overheard. 

There is no fee or charge for either an 
operator’s license or a station license. 



Variable Condenser 


41 













Broadcasting Stations 


Where 


Located 

State 

Camden . 

N. J. 

Newark . 

N. J. 

N ewark . 

N. J. 

Jersey City . 

N. J. 

Jersey City . 

N. J. 

New York .. 

N. Y. 

New York .. 

N. Y. 

New York .. 

N. Y. 

New Haven . 

Conn. 

Hartford . ... 

Conn. 

Springfield . . 

Mass. 

Medford 


** » Hillside 

. Mass. 

Worcester .. . 

Mass. 

Washington . 
Washington . 

D. C. 
D. C. 

Washington . 

D. C. 

Washington . 

D. C. 

Philadelphia 

. Pa- 

Pittsburgh .. 

Pa. 

Pittsburgh .. 

Pa. 

Indianapolis 

, Ind. 

Toledo. 

Ohio 

Cincinnati .. 

Ohio 

Detroit . 

Mich. 

Chicago . 

Ill. 

Madison .... 

. Wis. 

Omaha . 

Neb. 

Minneapolis , 

, Minn. 

Kansas City 

Mo. 

Lincoln ..... 

Neb. 

Denver .... 

Col. 

Denver .... 

Col. 

Los Altos . 

. Cal. 

Pasadena ... 

Cal. 

Los Angeles 

Cal. 

Los Angeles 

Cal. 

Los Angeles 

Cal. 

Hollywood . 

. Cal. 

Oakland ... 

. Cal. 

Oakland ... 

. Cal. 

Sacramento 

. Cal. 

(San Francisco Cal. 

San Francisco Cal. 

San Francisco Cal. 

San Jose .. 

. Cal. 

Stockton ... 

. Call. 

Stockton ... 

. Cal. 

Sunnyvale .. 

. Cal. 

Seattle . 

. Wash 


Station 

Call Operated by 
W P R Federal Institute of Radio 
WOR L. Bamberger & Co. 

W J Z Westinghouse Co. 

W N O Jersey Journal 
2AI Jersey Review 
W J X De Forest Radio Co. 
WDT Shipowners Radio Service 
WYCB Amateur Radio Reserve 
WCJ A. C. Gilbert Co. 

W Q B C. D. Tuska Co. 

W B Z Westinghouse Co. 

W G I Am. Radio Research Co. 
W C N Clark University 
W D N Church of the Covenant 
W D W Radio Construction Co. 
W J H White & Boyer Co. 

N O F Board of Health 
W I P Gimbel Bros. 

K D K A W T estinghouse Co. 

W P B Newspaper Printing Co. 
WLK Hamilton Mfg. Co. 

D W Z Marshall Gerken Co. 

W M H Precision Equipment Ca 
W B L Detroit News 
K Y W Westinghouse Co. 

W H A University of Wisconsin 
W O U R. B. Howell 
WLB University of Minnesota 
9 Z A B Western Radio Co. 

9 Y Y State University 
9 Z A F Revnolds Radio Co. 

K O A Y. M. C. A. 

K L B Colin B. Kennedy Co. 

K L B J. J. Dunn & Co. 

K 0 L Arno A. Kluge 
K Y J Leo J. Meyberg Co. 

K Z C Western Radio Electric Co 
K G C Electric Lighting Co. 

K Z M Preston D. Allen 
K Z Y Atlantic & Pac. Radio Sup 
ZVQ J. C. Hobrecht 
KDN Leo J. Meyberg Co. 
KGB Edwin L. Lorden 
K Y Y Radio Telephone Shop 
K Q W Charles D. Herrold 
K J Q C. O. Gould 
K W G Portable Wireless Tel. Co 
K J J The Radio Shop 
K F G N orthern Radio Electric Co. 


42 











Highpower Radio Stations 
United States and Possessions 


Location 

Call 

Wave Length 


NSS 

16900 

Arlington, Va . 

NAA 

6000 

Raifanfv ri. z.. 

NBA 

7000 

Poston Mass .. 

NAB 

5700 

Cavite, P- I. 

NPO 

12000 


NAO 

4700 


NPA 

7600 

Great Pa Ices. 

NAJ 

5700 

Guam Marianna Islands. 

NPN 

5000 


NAW 

4500 


NAR 

6500 


wso 

11500 


NFF 

13600 

New Orleans, Pa. 

NAT 

5500 

Pearl Harbor Hawaii. 

NPM 

11000 


NPC 

5250 


NPL 

13300 and 9800 

San Francisco, Cal. 

NPG 

8600 and 4800 


NAU 

5250 


NDD 

11600 and 9800 


NWW 

9200 


NPU 

6000 and 3000 





Great Britain and Other Countries 


Location 


Barrington Passage, N. S. . 

Bermuda, W. I . 

Camarron, Wales . 

Christiana, Jamaica . 

Hong Kong, China . 

Horsea, England . 

Punta, Delgada, Azores . 

Singapore, Malay Peninsula.. 

St. Johns, Newfoundland . 

Eiffel Tower, Paris . 

Lyons, France . 

Nantes, France . 

Rome, Italy . 

Hanover (Eilvese) , Germany . 

Nauen, Germany . 

Funabashi, Japan . 

Stavanger, Norway... . 

Java, Dutch East Indies . 


Call 

Wave Length 

VCU 

5000 

BZR 

5000 

MUU 

14000 

BZQ 

5000 

BXY 

5000 

BYC 

4500 

BWP 

2000 

VPW 

3400 

BZM 

5000 

FL 

10000 

YN 

15500 

VAUA 

9000 and 11000 

IDO 

11000 

OUI 

15000 

POZ 

12600 

JJC 

7700 

LCM 

9500 and 12000 

PMM-PMX 

6100 


43 





























































Miscellaneous Damped Wave Stations 


Location 

Call 

Wave Length 

Arlington, Va., U. S.. . 

NAA 

NJK 

VMG 

MFT 

GB 

VKT 

MPD 

VJZ 

2500 

1800 

2000 

6000 

7500 

2200 

2800 

2900 

1800 

6500 

5500 

4000 

5000 and 7000 

New Orleans, La., U.S.A., “WNU”. 

Apia, Samoa. 

Clifden, Ireland.. 

Glace Bay, N. S... 

Nauru, Pacific Ocean. 

Poldhu, Ireland. 

Rabaul, Pacific Ocean.... . 

Yap, Pacific Ocean... 

Coltano, Italy. 

ICI 

LP 

XDA 

TSR 

Berlin, Germany. 

Mexico City, Mexico. 

Petrograd, Russia. 


Tuning Coil Data 
Windings of Enameled Wire 


No. of 
WIRE 

B & S 
Gauge 

Diameter 

of 

wood 

CORE 

Feet of 
Wire per 

1 in. of 
Winding 

Wave 
length in 
meters per 

1 in. of 
Winding 

Turns of 
Wire per 

1 in. of 
Winding 

No. 26 

2" 

30 

37 

58 

No. 28 

2" 

38 

46 

73 

No. 24 

3" 

36 

44 

46 

*No. 26 

3" 

46 

56 

58 

*No. 24 

4" 

48 

59 

46 

♦No. 22 

5" 

49 

60 

37 

♦No. 22 

6" 

58 

70 

37 

No. 20 

7” 

55 

67 

30 

No. 20 

8" 

63 

77 

30 


No. of Wire on 
Loose Coupler 
Secondary 

Length of 
Primary and 
Secondary 

Wave length in 
Meters of Loose 
Coupler 

36 

4" 

700 

32 

5" 

800 

32 

6" 

1000 

32 

6" 

1200 


NOTES—To find meters wave length of any tuning coil, 
multiply its length in inches by wave length in meters 
per inch of winding. 


44 



































Dielectric Constants 


Dielectric 

Substance Constant 

Paraffined rice-paper.3.65 

Bees’ waxed rice-paper.2.53 

Shellacked rice-paper.3.60 to 4.25 

Mica sheet (pure).4.00 to 8.00 

Flint glass (light).6.85 

Common glass (radio frequency).3.25 to 4.21 

Common glass (audio frequency).3.02 to 3.09 

Castor oil.. .4.80 

Transformer oil.2.50 

Ebonite .2.05 to 3.15 

Air (at ordinary pressure).1.00 


Table of Resistivities and Conductivities 
of Metals 


Substances 


Specific Resistance Relative 
in Mxrohms Conductivity 
Per Cubic at Zero, 

Centimeter Centigrade 


Pure Silver. 1.49 

Refined Copper. 1.59 

Pure Gold (unalloyed). 2.04 

Aluminum (annealed). 2.89 

Swedish Iron. 10.08 

Platinum (pure). 11.00 

Lead . 19.63 

German Silver. 30.00 

Mercury . 94.30 


100.00 
99.90 
86 65 
63.09 
16.00 
10.60 
8.88 
7.70 
1.60 


Abbreviations of Units 


Unit Abbreviation 

Amperes . amp. 

Ampere—hours, amp.—hr. 

centimeters . cm. 

cycles per second . /'“"w 

kilometers . km. 

kilowatts . kw. 

kilowatt—hours, kw.—hr. 
kilovolt—amperes, .kva. 


Unit Abbreviation 

meters . m. 

microfarads . mf. 

millihenries . mh. 

millimeters . mm. 

square centimeters . . cm* 

volts . v. 

watts . w. 


45 










































Capacity of Fuse Wires 


Dia. in 
1/1,000 in. 

Copper 

Amperes 

Wires Tin 
Amperes 

Lead 

Amperes 

92 

286.0 

46.0 

38.0 

63 

166.0 

26.0 

22.2 

48 

105.0 

17.0 

14.0 

36 

70.0 

11.2 

9.4 

28 

48.0 

7.7 

6.5 

22 

33.5 

5.4 

4.5 

18 . 

24.8 

4.0 

3.35 

15 

18.4 

3.0 

2.5 

12 

14.1 

2.8 

2.0 

10 

11.5 

1.8 

1.5 

9 

9.0 

1.5 

1.2 

7 

6.8 

1.0 

.9 

6 

4.7 

.76 

.64 

4 

3.5 

.55 

.45 


Conversion Tables 


(1) Watts to Horse Power 


Watts 

Horse Power 

Kilowatts 

Horse Power 

1 

.0014 

. 5 

.670 

5 

.0067 

.75 

1.005 

10 

.0134 

1.0 

1.34 

20 

.0268 

2.0 

2.68 

25 

.0335 

3.0 

4.02 

30 

.0402 

4.0 

5.36 

40 

.0536 

5.0 

6.70 - 

50 

.067 

6.0 

8.04 

75 

.100 

7.0 

9.38 

100 

.134 

8.0 

10.0 

200 

.268 

9.0 

12.1 

250 

.335 

10.0 

13.4 


(2) Horse Power to Watts 


Horse Power 

Watts 

Horse Power 

Kilowatts 


46.62 

4 

2.984 

y% 

93.25 

5 

3.730 


186.5 

6 

4.476 

y 

373.0 

7 

5.222 

% 

559.5 

8 

5.968 

l 

746.0 

9 

6.714 

2 

1492.0 

10 

7.460 

3 

2338.0 

20 

14.920 


46 

































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9800 Undamped. 

San Francisco, Cal. . .N P G 2400 Noon, 10 P. M., 120th Meridian, Standard Time. 
Great Lakes, Ill.NAJ 1512 11 A. M., 90th Meridian, Standard Time. 











WIRELESS ALPHABET 
Dot and Dash Code 


A • 1 
B ■### 

C — • " • 

D — • • 

E _•_ 

F • • wm • 

H • • • • 

I • • _ 

L • M • • 

N M • 

O M M 
P • ■ 1 # 

Q 

R »■ t 

S 

U • • — 

v • • • m 


w 

x 

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z 





51 


























































SYMBOLS USED IN RADIO WORK 


KEY. 


RESISTOR 


-AAA/VW 


VARIABLE AAA A AAA_ 

RESISTOR- - 


SWITCH S.P. S.T. 

•* S.P.DT.. 

•* D.P.S.T. 

•* D.P.D.T. 






•• REVERSING 


tel r e e p c h e TvIr— X OR (5b 

la 

-AL 


TELEPHONE_ 

TRANSMITTER 


THERMOELEMENT. 


TRANSFORMER-; - or 


VACUUM TUBE-- 

VOLTMETER 

82 



...— 

















ALTERNATOR^— 


AMMETER 


ANTENNA. 


ARC 


BATTERY_ 


BUZZER__ 


CONDENSOR 


VARIABLE 

CONDENSER 

CONNECTION- 

OF WIRES 


NO CONNECTION 


COUPLED COILS_ 


VARIABLE COUPLING 


DETECTOR 







GALVANOMETER 

GAP. PLAIN__• •- 

GAP. QUENCHED-|||]||||^— 


GROUND. 


INDUCTOR.. 


immr 


53 













WHAT HAPPENS IN A 
RECEIVING SET 

The aerial is placed in such a position 
that it can pick-up or catch the radio waves 
(electro-magnetic waves), these waves hav¬ 
ing been set in motion at the transmitting 
or broadcasting station and travel from this 
station through space at the rate of 186,000 
miles per second. As soon as these waves 
set up oscillations in the receiving aerial, 
a current is passed from the aerial down 
the lead-in wire to the primary coil of the 
transformer. The action of the current in 
this coil sets up a magnetic field, this cur¬ 
rent is induced into the secondary coil of 
the transformer and this produces a radio 
frequency current which is gradually built 
up by adjusting the primary and secondary 
in electrical resonance. The variable con¬ 
denser is placed in the circuit to allow the 
secondary circuit to be adjusted to resonance 
with the primary circuit and also to allow 
of close adjustment. The induced current 
will overflow to the detector circuit as soon 
as the secondary circuit lias been put in 
resonance with the primary circuit. The 
detector will then rectify this current by 
transforming the high frequency to low fre¬ 
quency. The current then passes to the 
condenser where it is stored; as soon as a 
single wave train has accumulated in the 
condenser, the condenser will discharge 
the current into the phone receivers where 
by its action in vibrating the diaphragm it 
makes the magnetic waves received by the 
aerial audible to the ear. 


r,4 


WHAT IS MEANT BY 
WAVELENGTH 

Electric-magnetic waves like light waves 
travel at the rate of 186,000 miles or 300,- 
000,000 meters per second, if we are using 
an alternating current of 25,000 cycles per 
second and cause a disturbance in the air 
of that frequency then each cycle will travel 
from the aerial through space at the rate of 
300,000,000 meters per second. So that at 
the end of the second, just as we are caus¬ 
ing the last of the 25,000 disturbances the 
first cycle or disturbance is 300,000,000 
meters away. In one second we have made 
25.000 separate disturbances which have 
traveled 300,000.000 meters each disturbance 
separated by the number of meters that 
25.000 divided into 300,000.000 will give— 
300,000.000 divided by 25,000 equals 12,000 
meters—it is this distance between the sep¬ 
arate disturbances that is known as the 
wavelength. 

RULE FOR WAVELENGTH 

Add the length of the aerial to the lead- 
in wire. Add to the sum the ground and 
if more than one wire, one-third of length 
of aerial. Divide this total by two and add 
the result to the addition above. The an¬ 
swer will give the approximate wavelength 
in meters.—Example—Length of aerial 100 
feet, length of ground wire 40 feet, length 
of lead-in wire 20 feet— 100 4- 40 4- 20 
equals 160 feet. One-third of 100 equals 
33 -f- 160 equals 193. 193 divided by 2 equals 
96, 193 -f 96 equals 284 which is the ap¬ 
proximate wavelength in meters. 


55 


FIXED CONDENSER 

Fixed condensers are used as shunts 
across the detector to intensify the incom¬ 
ing signals and to permit of fine tuning. 
To make a fixed condenser, first cut a num¬ 
ber of strips of tin foil into sheets measur¬ 
ing 3 inches by 2 inches wide. Then lay 
two pieces of paraffined paper on the top 
of a cardboard measuring 3 inches long by 
2 inches in width. Then, on top of these 
sheets of paraffined paper lay one of the 
strips of tin foil leaving about inch pro¬ 
jecting over the end of the paraffined paper 
under it and, on top of this lay another 
strip of tin foil, this time letting it project 


Fixed Condenser. 

— , 1 

Sheet of Tinfoil. 

Tahaffined -paper [ 



56 






















J4 inch over the paraffined paper on the 
opposite end. And so on, the condenser 
being- built with alternate layers of paraf¬ 
fined paper and tin foil, until the desired 
number of sheets have been built up. Place 
two pieces of the paraffined paper on top 
and over this a strip of cardboard, the same 
size as that at the bottom. The whole thing 
is then bound up with thread. Now, lay 
the condenser on a board fixing on two 
binding posts, so that they clamp down the 
projecting ends of tin foil to the wood base. 
The condenser is then ready for use in the 
circuit. 


TUNING 

The apparatus for tuning a receiving set 
consists of an adjustable circuit containing 
variable capacity and inductance. The 
operation of the tuning apparatus is ve.ry 
simple. We have already seen that this ap¬ 
paratus is used to vary the wave length of 
the receiving set, making it receptive to 
incoming signals. As in order to receive 
signals, the receiving set must be adjusted 
so that the receiving circuits a*re in tune 
with the transmitting circuit's. In other 
words, the time period of oscillation must 
be the same in both the transmitting and 
receiving circuits. Thus should we desire 
to receive the music or speeches from a 
broadcasting station using a 360 meter 
wavelength, then it would be necessary for 
us to adjust our receiving set to as near 
that wavelength as possible to get maxi¬ 
mum results. 


57 


HOW TO MAKE A 
TUNING COIL 

A simple tuning or loading coil consists 
of a cardboard tube around which a wire is 
wound, and so arranged that more or less 
of this wire can be cut in or out of the cir¬ 
cuit by means of a sliding contact point. 
To build the coil you will need the follow¬ 
ing : _A cardboard tube 18 or 20 inches long 
and about 4 inches in diameter, V /2 lbs. of 
No. 24 copper wire, 2 brass rods a trifle 
longer than the cardboard tube and approx¬ 
imately Ya inch square. Two wood discs, 
Ys of an inch thick and just large enough to 
fit tightly into the ends of the cardboard 
tube, two wood pieces for ends, about 4J4 
inches square and a wood base to mount 
the .whole affair on. First wind the wire 
tightly around the whole length of the card¬ 
board tube, leaving a free end of wire at 
each end of the tube. Care should be taken 
to space the winding evenly. Next, mount 
the two wood discs in the center of the two 
wood end pieces. Then slip the discs, one 
into each end of the cardboard tube and 
mount the whole affair on the wood base. 
It is now necessary to mount the brass 
rods in such a manner that the sliding con¬ 
tacts on the rod make a good contact on 
the wire windings of the coil. One end 
of the wire windings is attached to a bind¬ 
ing post while the other end is passed 
through a hole in the cardboard tube, so 
that it will be out of the way. It will be 
found advisable to dry all wood used in the 
building of Radio apparatus, by leaving it 
for an hour or two in a warm oven, then 
giving it a coat of shellac. This will elim- 


58 


ftA S5 
-Ron 




■to 


END V/£¥V ok)-Cs(D£ 











inate shrinking or warping of the wood. 
The.re are various makes of coils on the 
market and I do not think it advisable to 
go to the trouble of constructing one, as 
long as they can be bought so cheaply. A 
number of beginners, however, like to build 
their own, and it is for them that this 
article is written. 





A COMPLETE RECEIVING SET ON 
A COMMON BASE 

A—Connection to Aerial. 

B—Wood End Pieces. 

C—Brass Rods. 

D—Connection to Ground. 

El—Sliding Contacts. 

F—Phone Connections. 

G—Crystal and Holder. 

H—Adjustable Cat Whisker Holder. 

J—Fixed Condenser. 

K—Cat Whisker. 


60 






DETECTOR AND TWO STAGE AMPLIFIER 



61 


Designed to Operate With One Radiotron Detector Tube and 

Two Radiotron Amplifier Tubes. 







What Do You Know About Radio? 
Here’s the Book That Tells You All— 


Radio for the Beginner 

‘By JAMES R. CAMERON 

A few of the chapters this compre¬ 
hensive work contains: 

Construction of Receiving Sets—Operation 
of Receiving Sets—What Happens in a 
Receiving Set—What Happens in a Trans¬ 
mitting Set— How We Hear Music by Wire¬ 
less—What is Meant by Tuning—What is 
Meant by Wavelength—Radio Troubles, 
Their Cause and Remedy — Wiring of 
Regenerative Receiving Sets—Aerials and 
Their Uses—Care of Storage Batteries— 
Lightning Protective Devices—Loud Speak¬ 
ers—Radio Attachments for the Victrola 
—Vacuum Tubes—Wiring Diagrams—Con¬ 
struction of a Crystal Set— How to Make 
a Fixed Condenser— How to Make a Vari¬ 
able Condenser— How to Make a Vario¬ 
meter—How to Make a Reactance Coil— 
How to Make a Crystal Detector— How to 
Make a Vario-Coupler—Requirements for 
Radio Installation — Inductance — Trans¬ 
formers — Alternating Currents — Genera¬ 
tion of Electricity—Useful Tables and In¬ 
formation—Radio Rules and Regulations— 
Location of Faults—Installation of Ap¬ 
paratus 

£ 1.00 

Write for Your Copy Today 

THE TECHNICAL BOOK COMPANY 

130 West 42nd Street New York City 


62 


HOW TO BUILD AND OPERATE 
A CRYSTAL DETECTOR 
RECEIVING SET 

Having been asked by the publishers of this 
book to include an article on the construction 
operation, and care of a crystal-detector set, 
that can easily be built at home at very little 
expense. The writer knows of no better article 
than the one prepared by the U. S. Bureau 
of Standards at the request of the States 
Relations Service of the Dept, of Agriculture. 
The following is part of the article and tells 
in simple language how a set can be built at 
an outlay of approximately Seven Dollars (not 
including the phone receiver) : 

The parts will be mentioned here by refer¬ 
ence to the letters appearing in Figs. 1 and 2. 

A and I are screw eyes sufficiently strong to 
anchor the antenna at the ends. 

B and H are pieces of rope H or Y /i inch in 
diameter, just long enough to allow the an¬ 
tenna to swing clear of the two supports. 

D is a piece of Vs or l / 2 inch rope sufficiently 
long to make the distance between E and G 
about 75 ft. 

C is a single-block pulley which may be used 
if readily available. 

E and G are two insulators which may be 
constructed of any dry hard wood of sufficient 
strength to withstand the strain of the antenna; 
blocks about I^x2xl0 in. will serve. The 
holes should be drilled as shown in Fig. 1 
sufficiently far from the ends to give proper 
strength. If wood is used the insulators should 
be boiled in paraffin for about 1 hour. If 
porcelain wiring cleats are available they may 
be substituted instead of the wood insulators. 
If any unglazed porcelain is used as insula¬ 
tors, it should be boiled in paraffin the same 
as the wood. Regular antenna insulators are 


advertised on the market, but the two im¬ 
provised types just mentioned will be satis¬ 
factory for an amateur receiving antenna. 

F is the antenna about 75 ft. between the 
insulators E and G. The wire may be No. 14 
or 16 copper wire either bare or insulated. 
The end of the antenna farthest from the re¬ 
ceiving set may be secured to the insulator 
(E) by any satisfactory method, being careful 
not to kink the wire. Draw the other end 
of the antenna wire through the other in¬ 
sulator (G) to a point where the two insula¬ 
tors are separated by about 75 ft., twist the 
insulator (G) so as to form an anchor as 
shown in Fig. 1. The remainder of the an¬ 
tenna wire (J) which now constitutes the 
"lead-in” or drop-wire should be just long 
enough to reach the lightning switch. 

K is the lightning switch. For the purpose 
of a small antenna this switch may be the or¬ 
dinary porcelain-base, 30 ampere, single-pole 
double-throw battery switch. These switches 
as ordinarily available, have a porcelain base 
about 1 by 4 in. The ‘‘lead-in” wire (J) is 
attached to this switch at the middle point. 
The switch blade should always be thrown 
to the lower clip when the receiving set is not 
actually being used and to the upper clip when 
it is desired to receive signals. 

L is the ground wire for the lightning 
switch; it may be a piece of the same size 
wire as used in the antenna, of sufficient length 
to reach from the lower clip of the lightning 
switch (K) to the clamp on the ground red 

(M) \ 

M is a piece of iron pipe or rod driven 
3 to 6 ft. into the ground, preferably where 
the ground is moist, and extending a sufficient 
distance above the ground in order that the 
ground clamp may be fastened to it. Scrape 


64 


the rust or paint from the pipe before driving 
in the ground. 

N is a wire leading from the upper clip of . 
the lightning switch through the porcelain tube 
(O) to the receiving set binding post marked 
“antenna.” 

O is a porcelain tube of sufficient length to 
reach through the window casing or wall. 
This tube should be mounted in the casing or 
wall so that it slopes down toward the outside 
of the building. This is done to keep the rain 
from following the tube through the wall to 
the interior. 

Fig. 2 shows the radio receiving set installed 
in some part of the house. 

P is the receiving set which is described in 
detail below. 

N is the wire leading from the “antenna” 
binding post of the receiving set through the 
porcelain tube to the upper clip of the light¬ 
ning switch. This wire, as well as the wire 
shown bv Q. should be insulated and prefer- 
ablv flexible! A piece of ordinary lamp cord 
might be unbraided and serve for these two 
leads. 

Q is a piece of flexible wire leading from 
the receiving set binding post marked “ground” 
to a water pipe, heating system or some other 
metallic conductor to grourd. except M. Fig. 1. 
f If there are no water pipes nor radiators in 
the room in which the receiving set is located, 
the wire should he run out of doors and con- 
f nected to a special “ground” below the win¬ 
dow, which shall not be the same, as the 
“ground” for the lightning switch. It is essen¬ 
tial that for the best operation of the receiving 
set this “ground” he of the very, best type. If 
; the soil near the house is dry it is necessary 
to drive one or more pipes or rods sufficiently 
i deep to encounter moist earth and connect the 
* ground wire to the pipes or rods. This dis- 



tance will ordinarily not exceed 6 ft. Where 
clay soil is encountered this distance may be 
reduced to 3 ft., while in sandy soil it may be 
increased to 10 ft. If some other metallic con¬ 
ductor, such as the casing of a drilled well, is 
not far away from the window, it will be a 
satisfactory “ground.” 

Tuner, Detector and Phone 

The detector and phone will have to be 
purchased. The tuner and certain accessories 
can be made at home. 

Tuner (R, Fig. 3 )—This is a piece of card¬ 
board or other non-metallic tubing with turns 
of copper wire wound around it. The card¬ 
board tubing may be an oatmeal box. Its con¬ 
struction is described in detail below. 

Crystal Detector (S, Fig. 3 )—The construc¬ 
tion of a crystal detector may be of very sim¬ 
ple design and quite satisfactory. The crystal, 
as it is ordinarily purchased, may be unmounted 
or mounted in a little block of metal. For me¬ 
chanical reasons the mounted type may be more 
satisfactory, but that is of no great conse¬ 
quence. It is very important, however, that 
a very good tested crystal be used. It is prob¬ 
able also that a galena crystal will be more 
satisfactory to the beginner. 

The crystal detector may be made up of a 
tested crystal, three wood screws, short piece 
of copper wire, a nail, set-screw type of bind¬ 
ing post, and a wood knob or cork. The tested 
crystal is held.in position on the wood base 
by three brass wood-screws as shown at 1, 
Fig. 3. A bare copper wire may be wrapped 
tightly around the three brass screws for con¬ 
tact. The assembling of the rest of the crystal 
detector is quite clearly shown in Fig. 3. 

Phone (T, Fig. 3 )—It is desirable to use a 
pair of telephone receivers connected by a 

66 


head band, usually called a double telephone 
headset. The telephone receivers may be any 
of the standard commercial makes having a 



resistance of between 2000 and 3000 ohms. The 
double telephone receivers will' cost more than 
all the other parts of the station combined, 




67 














































but it is desirable to get them, especially if 
one plans to improve his receiving set l^ter. 
If one does not care to invest in a set of 



double telephone receivers, a single telephone 
receiver with a head band may be used;; ,, it 
gives results somewhat less satisfactory. ; 


08 
































































Accessories —Under the heading of accessory 
equipment may be listed binding posts, switch 
arms, switch contacts, test-buzzer, dry battery, 
and boards on which to mount the complete 
apparatus. The binding posts, switch arms and 
switch contacts may all be purchased from 
dealers who handle such goods or they may 
be quite readily improvised at home. There 
is nothing peculiar about the pieces of wood 
on which the equipment is mounted. They 
may be obtained from a dry packing-box and 
covered with paraffin to keep out moisture. 

Details of Construction 

The following is a detailed description of 
the method of winding the coil, construction 
of the wood panels, and mounting and wiring 
the apparatus: 

Tuner —See R, Fig. 3. Having supplied one¬ 
self with a piece of cardboard tubing 4 in. in 
diameter and about J4 pound of No. 24 (or 
No. 26) double cotton covered copper wire, 
one is ready to start the winding of the tuner. 
Punch two holes in the tube about J /2 in. from 
one end as shown at 2 on Fig. 3. Weave the 
wire through these holes in such a way that 
the end of the wire will be quite firmly an¬ 
chored, leaving about 12 inches of the wire 
free for connections. Start with the remainder 
of the wire to wrap the several turns in a 
single layer about the tube, tightly and closely 
together. After 10 complete turns have been 
wound on the tube hold those turns snugly 
while a tap is being taken off. This tap is 
made by making a 6 in. loop of the wire and 
twisting it together at such a place that it 
will be slightly staggered from the first tap, 


This method of taking off taps is shown quite 
clearly at U, Fig. 3. Proceed in this manner 
until 7 twisted taps have been taken off at 
every 10 turns. After these first 70 turns have 
been wound on the tube then take off a 6 in. 
twisted tap for every succeeding single turn 
until 10 additional turns have been wound 
on the tube. After winding the last turn of 
wire anchor the end by weaving it through 
two holes punched in the tube much as was 
done at the start, leaving about 12 in. of wire 
free for connecting. It is to be understood 
that each of the 18 taps is slightly staggered 
from the one just above, so that the several 
taps will not be bunched along one line on 
the cardboard tube. See Fig. 3. It would 
be advisable, after winding the tuner as just 
described, to dip the tuner in hot paraffin. 
This will help to exclude moisture. 

Upright Panel and Base —Having completed 
the tuner to this point, set it aside and con¬ 
struct the upright panel shown in Fig. 4. This 
panel may be a piece of wood approximately 
54 in. thick. The position of the several holes 
for the binding posts, switch arms and switch 
contacts may first be laid out and drilled. The 
"antenna” and '‘ground” binding posts may 
be ordinary % in. brass bolts of sufficient length 
and supplied with three nuts and two washers. 
The first nut binds the bolt to the panel, the 
second nut holds one of the short pieces of 
stiff wire, while the third nut holds the an¬ 
tenna or ground wire as the case may be. 
The switch arm with knob shown at V, Fig. 3, 
may be purchased in the assembled form or it 
may be constructed from a thin slice cut from 
a broom handle and a bolt of sufficient length 
equipped with four nuts and two washers to- 


70 


gether with a narrow strip of thin brass some¬ 
what as shown. The switch contacts (W, 
Fig. 3) may be of the regular type furnished 



for this purpose or they may be brass bolts 
eauipped with one nut and one washer each 
or thev may even be nails driven through the 


71 













































































































panel with an individual tap fastened under 
the head or soldered to the projection of the 
nail through the panel. The switch contacts 



should be just close enough that the switch 
arm will not drop between the contacts, but 
also far enough apart that the switch arm 


72 

















can be set so as to touch only one contact at 
a time. 

The telephone binding post should preferably 
be of the set screw type as shown at X, Fig. 3. 

Instructions for Wiring 

' Having constructed the several parts just 
mentioned and mounted them on the wood 
base, one is ready to connect the several taps 
to the switch contacts and attach the other 
necessary wires. Scrape the cotton insulation 
from the loop ends of the sixteen twisted taps 
as well as from the ends of the two single taps 
coming from the first and last turns. Fasten 
the bare ends of these wires to the proper 
switch contacts as shown by the corresponding 
numbers in Fig. 3. One should be careful not 
to cut or break any of the looped taps. It 
would be preferable to fasten the connecting 
wires to the switch contacts by binding them 
between the washer and the nut as shown at 
3. Fig. 3. A wire is run from the back of the 
binding post marked “ground” (Fig. 3) to 
the back of the left-hand switch-arm bolt (Y), 
thence to underneath the left-hand binding 
post marked “phones.” A wire is then run 
from underneath the right-hand binding post 
marked “phones” to underneath the binding 
post (4, l ; ig. 3), which forms a part of the 
crystal detector. A piece of* No. 24 bare cop¬ 
per wire about 2^2 in. long, one end of which 
is twisted tightly around the nail (the nail 
passing through binding post 4), the other end 
of which rests gently by its own weight on 
the crystal (1). The bare copper wire which 
was wrapped tightly around the three brass 
wood-screws holding the crystal in place is lead 
to and fastened at the rear of the right-hand 
switch arm bolt (v), thence to the upper left- 
hand binding post marked “antenna.” As 


73 


much as possible of this wiring is shown in 
Fig. 3. 

Directions for Operating 

After all the parts of this crystal-detector 
radio receiving set have been constructed and 
assembled the first essential operation is to 
adjust the little piece of wire, which rests 
lightly on the crystal, to a sensitive point. 
This may be accomplished in several different 
ways; the use of a miniature buzzer trans¬ 
mitter is very satisfactory. Assuming that the 
most sensitive point on the crystal has been 
found by method described in paragraph below, 
“The Test Buzzer,” the rest of the operation 
is to get the radio receiving set in resonance 
or in tune with the station from which one 
wishes to hear messages. The tuning of the 
receiving set is attained by adjusting the in¬ 
ductance of the tuner. That is, one or both 
of the switch arms are rotated until the proper 
number of' turns of wire of the tuner are 
made a part of the metallic circuit between 
the antenna and ground, so that together with 
the capacity of the antenna the receiving cir¬ 
cuit is in resonance with the particular trans¬ 
mitting station. It will be remembered that 
there are 10 turns of wire between each of the 
first 8 switch contacts and only one turn of 
wire between each 2 of the other contacts. The 
tuning of the receiving set is best accomplished 
by setting the right-hand switch arm on con¬ 
tact (1) and rotating the left-hand switch 
arm over all its contacts. If the desired sig¬ 
nals are not heard, move the right-hand switch 
arm to contact (2) and again rotate the left- 
hand switch arm throughout its range. Pro¬ 
ceed in this manner until the desired signals 
are heard. 

It will be advantageous for the one using 
this radio receiving equipment to find out the 


74 


wave frequencies (wave-length) used by the 
several radio transmitting stations in his im¬ 
mediate vicinity. 

The Test Buzzer (Z, Fig. 3)—As mentioned 
previously, it is easy to find the more sensitive 
spots on the crystal by using a test buzzer. 
The test buzzer is used as a miniature local 
transmitting set. When connected to the re¬ 
ceiving set as shown at Z, Fig. 3, the current 
produced by the buzzer will be converted into 
sound by the telephone receivers and the 
crystal, the loudness of the sound depending 
on what part of the crystal is in contact with 
the fine wire. To find the most sensitive spot 
connect the test buzzer to the receiving set as 
directed, close the switch (5, Fig. 3) (and if 
necessary adjust the buzzer armature so that 
a clear note is emitted by the buzzer), set the 
right-hand switch arm on contact point No. 8, 
fasten the telephone receivers to the binding 
posts marked “phones,” loosen the set screw 
of the binding post slightly and change the 
position of the fine wire (6, Fig. 3) to several 
positions of contact with the crystal unit until 
the loudest sound is heard in the phones, then 
tighten the binding post set screw (4) slightly. 



Fixed Condenser 


75 


How to 

Build Your Own 


Receiving Set 


Full instructions 
with diagrams and 
drawings, making 
it easy for the be¬ 
ginner to build his 
own set and listen 
in to the daily 
concerts 



cents 


From Your Dealer or 
Direct from 


THE 

TECHNICAL BOOK CO. 


Bush Building 


130 West 42nd St., New York City 


76 



REQUIREMENTS OF NATIONAL 
ELECTRICAL CODE-RADIO 
INSTALLATION 

Where an indoor aerial is used, no special 
safe-guards are necessary, but where the aerial 
is placed outside the building, a ground wire 
should be carried from the aerial in the most 
direct line to the ground. This wire should 
not be smaller than No. 8 B & S gauge. 
Should it not be possible to make a suitable 
ground connection outside the building, then 
the ground wire should be lead into the cellar 
of building through a lead-in insulator and 
connection made to the water main. Do not 
under any circumstances connect the ground 
wire to a gas pipe. The lead-in wire from 
the aerial to the receiving set shoul be pro¬ 
tected by one of the approved types of light¬ 
ning arrestors now on the market. This ar¬ 
restor should be installed on the lead-in wire 
outside the building. 

A. Aerial conductors must be installed and 
constructed to prevent accidental contact with 
the conductors carrying a current over 600 volts. 
Aerial supports must be constructed and in¬ 
stalled in a strong and durable manner. Aerial 
wires leading from same to ground switch must 
be mounted firmly on approved insulating sup¬ 
ports which may be constructed of wood, not 
iron pin. or brackets equipped with porcelain 
knobs or petticoat insulators. Insulators must 
be so installed as to maintain the conductors at 
least five inches clear of the surface of the 
building wall. In passing the aerial conductor 
through the side of the building a continuous 
tube or bushing must extend five inches beyond 
the surface of the wall on both sides. The 
porcelain tube will not be approved in this 
case. Ground switches shall be mounted so 
that the current carrying parts will be at 
least five inches clear of the building walls and 


77 


located preferably in the most direct line be¬ 
tween the aerial and the point of ground con¬ 
nection. The conductor from the ground 
switch to ground connection must be securely 
supported. 


B. Aerial conductors must be effectively 
and permanently grounded at all times when 
the station is not in operation, by a conductor 
the periphery of the cross section of which is 
not less than three-quarters of an inch. The 
ground conductor must be of copper or other 
metal which will not corrode excessively under 
existing conditions. Where ground_ conductor 
is over twenty-five feet in length it shall be 
insulated throughout its entire length in a , 
similar manner to wires attached to aerial con¬ 
ductors. Ground connections should be made 
in accordance with the requirements as set 
forth above, except where variations from 
these requirements may be allowed by special 
permission in writing from the Board of Fire 
Underwriters. 


C. In radio stations used for receiving only 
the ground switch may be replaced by a simi¬ 
larly mounted and grounded short (one-eighth 
inch or less) or vacuum type lightning ar¬ 
restor. The current carrying parts must be t 
five inches from the building. 


D. Where the aerial is grounded as specified 
in sections A and B the switch employed to 
join the aerial to the ground connection must 
be a knife switch, the blade of which must 
have a periphery of not less than three-quar¬ 
ters of an inch so that when open the current 
carrying parts to which the aerial and ground 
connection wires are attached will be separated 
at least by five inches. The base of the switch 
must be of a material suitable for high fre- 
qency service. Slate will not be approved. 


78 





E. When supply is obtained direct from 
street service the current must be installed in 
metal conduit or armored cable. In order to 
protect the supply system from high potential 
surges there must be provided two condensers, 
each of not less than one-half microfarad 
capacity and capable of withstanding 600-volt 
tests in series across the line with mid-point 
grounded. A capacity fuse not larger than ten 
amperes capacity must be connected between 
each condenser and the line wire connected to 
it. Each condenser must be protected by a 
shunting fixed spark gap of one thirty-second 
of an inch separation or less. Another way 
of protecting the supply system from high po¬ 
tential surges is by means of two incandescent 
lamps connected in series across the line with 
the mid-point grounded. 


F. Transformer, voltage reducers, keys and 
similar devices must be of types specially de¬ 
signed for the service. 



Crystal Detector 


79 




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